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Coughing in thoroughbred racehorses: risk factors and tracheal endoscopic and cytological findings
  1. R. M. Christley, BVSc,PhD, MRCVS1,1,
  2. D. R. Hodgson, BVSc, PhD1,
  3. R. J. Rose, DVSc, PhD,FRCVS1,
  4. J. L. Hodgson, BVSc, PhD1,
  5. J. L. N. Wood, BSc,BVetMed, MSc, PhD,MRCVS2 and
  6. S. W. J. Reid, BVMS, PhD,MRCVS3,2
  1. 1 Department of Veterinary Clinical Sciences, University of Sydney, NSW 2006, Australia
  2. 2 Centre for Preventive Medicine, Animal Health Trust, Newmarket CB8 7DW
  3. 3 Veterinary Informatics and Epidemiology, Department of Veterinary Clinical Studies, University of Glasgow, Glasgow G61 1QH


A matched case-control study was made of 100 thoroughbred horses which were coughing and 148 control horses which were free of clinical signs of respiratory tract disease. The variables identified by multivariable conditional logistic regression as being significantly associated with coughing included age (the risk decreased with age), the stage of training (horses in early training were at greatest risk), the time since the last race (horses that had never raced were at greatest risk) and the time since they were last transported (horses transported more than 14 days previously were more likely to cough than those transported within the last week). The coughing horses were significantly more likely to have high scores for upper and lower tracheal mucus and pharyngeal lymphoid hyperplasia. In addition, the tracheal aspirates of the coughing horses had increased odds of neutrophilia and were more likely to have intracellular bacteria than the control horses. However, a considerable proportion of the control horses had cytological and/or endoscopic evidence of airway inflammation.

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  • Dr Christley's present address is Division of Equine Clinical Studies, Department of Veterinary Clinical Studies, University of Glasgow, Glasgow G61 1QH

  • Professor Reid is also at Department of Statistics and Modelling Science, University of Strathclyde, Glasgow GI 1XH

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